The present invention relates to making ice cubes in a horizontally oriented freezing tray having refrigerant and evaporator conduits integral with, and in intimate contact with, the ice cube mold compartments of a freezing tray, so that the resultant ice cubes have a long shelf life before melting.
Commercial ice in convenient sizes for mobile food carts, market produce, or fish displays is needed in large quantities. However, especially in warm weather, the ice melts quickly and must be replenished several times per day.
Many ice making machines make ice in vertically oriented freezing trays. In vertical dripping, the later dripped water freezes differently than the earlier dripped water in a vertical cascade. In addition, freezing is inhibited because the vertical inflow of water releases more energy as the water cascades down, thus slowing the freezing time due to the activity of the flowing, cascading water.
Among relevant vertically oriented ice making patents include U.S. Pat. No. 4,474,023 of Mullins for an ice making machine. In Mullins ""023, ice is formed by dripping water in vertically disposed trays, freezing the water into cubes, loosening the cubes by applying heat through adjacent evaporator conduits, then rotating the trays approximately 30 degrees downward from a vertical position, thereby dumping the formed ice cubes into a bin. Flexible hoses are used in Mullins ""023 for transporting both the water and the refrigerant in order to allow pivoting of the freezing tray from the vertical water loading position to the partially face-down dumping position. Mullins ""023 uses a high heat source in a cycle reversal for causing temporary loosening of the cubes from their individual molds within the tray, but the evaporator is attached to the tray, not integrally formed therewith. As a result, the tray contacting surface of the ice cubes is not uniformly and quickly heated for a quick melt and release therefrom.
A similar ice cube making machine with a vertically oriented freezing tray is described in U.S. Pat. No. 4,459,824 of Krueger. However, the vertical orientation of Mullins ""023 and Krueger ""824 increases drip inflow time, which provides a barrier to super-cooling of the water for forming the ice.
U.S. Pat. No. 4,255,941 of Bouloy describes an ice making machine which is vertically oriented. In Bouloy ""941, there are shown two freezing trays 22 welded back-to-back, wherein the trays 22 with semi-circular molds 32 for each ice cube have spaces 48 between the trays 22 for a reverse flow of alternately flowing refrigerant and evaporator gas. The hot gas is used to melt the ice cubes 124 from their molds 32 in each of the two back-to-back freezing trays 22.
The spaces 48 of Bouloy ""941 are arcuate triangles formed between the rounded backs of the semi-circular molds 32 forming the ice cubes.
The disadvantage of Bouloy ""941 is that since the two molds are welded back-to-back, at the weld seams between the two molds each labeled 22, the refrigerant and alternately the hot gas can""t flow through these closed seams, so there is not uniform intimate contact of the hot gas with the bottom of each ice cube mold 32 of each of the freezing trays 22.
U.S. Pat. No. 4,199,956 of Lunde describes an ice cube making machine which requires an electronic sensor to interrupt the freezing cycle to thaw the cubes for dumping.
U.S. Pat. No. 6,233,964 of Ethington describes an ice cube making machine with a freezing cycle and a hot gas defrost valve used with a detector for detecting frozen ice. Ethington ""964 is similar to conventional ice making machines in hotels and other commercial establishments.
Among other U.S. Patents for loosening frozen ice cubes from a tray ice include U.S. Pat. No. 3,220,214 of Cornelius for a spray type ice cube maker.
Moreover, among patents which heat trays for loosening ice cubes include U.S. Pat. No. 5,582,754 of Smith, which uses electrical heating elements to thaw semi-circular ice cubes from a freezing tray. In addition, U.S. Pat. No. 1,852,064 of Rosenberg, U.S. Pat. No. 3,318,105 of Burroughs, U.S. Pat. No. 2,112,263 of Bohannon U.S. Pat. No. 2,069,567 of White and U.S. Pat. No. 1,977,608 of Blystone also use electrical heating elements to thaw cubic ice cubes from a freezing tray. In Bohannon ""263, Burroughs ""105 and White ""567, the electrical heating elements are arrayed in longitudinally extending heating elements which extend adjacent to the sides and bottoms of ice cube freezing tray ice cube forming compartments, but the heating elements do not provide uniform heat all along an under-surface of each ice cube tray compartment.
U.S. Pat. No. 2,941,377 of Nelson uses serpentine conduits of evaporation fluid for loosening ice cubes, but only along the sides of the ice cube tray molds.
U.S. Pat. No. 1,781,541 of Einstein, U.S. Pat No. 5,218,830 of Martineau and U.S. Pat No. 5,666,819 of Rockenfeller and U.S. Pat. No. 4,055,053 of Elfving describe refrigeration units or ice making machines which utilize heat pumps for alternate heat and cooling.
Therefore, the prior art patents have the disadvantage of not allowing for supercooling of water on a horizontally oriented tray, and not allowing for rapid but effective heating of all of the undersurface of each ice cube from adjacent evaporator conduits conforming to the surface of the ice cube forming tray compartment molds, to provide only a slight melting of the undersurface of each ice cube for lubricating each cube prior to dumping in a supercooled state into a collection harvesting bin.
Furthermore, among the vertically oriented ice making machines such as of Mullins ""023 or Bouloy ""941, there is no way to use the freezing trays horizontally as a display counter, such as in a fish market or retail store.
It is therefore an object of the present invention to provide super-cooled ice cubes with a long shelf life before melting, and to improve over the disadvantages of the prior art.
It is yet another object of this invention to maximize the use of a horizontally oriented freezing tray of an ice making machine, wherein the horizontally oriented freezing tray has integral hollow sleeves in intimate contact with the freezing tray, to facilitate the rapid freezing and discharge of the ice from the freezing tray.
Other objects which become apparent from the following description of the present invention.
In keeping with these objects and others which may become apparent, the present invention is an efficient method of producing this commodity of melt-resistant ice is described by this invention. The method and apparatus of this invention uses one or more horizontally oriented freezing trays in combination with conventional vapor compression refrigeration using common refrigerants such as, for example, xe2x80x9cFree Environmental Refrigerant number 404Axe2x80x9d. The quality of the product is superior as the apparatus outputs ice segments that are supercooled (below or near 0 degrees F.) well below freezing temperature thus affording even more cooling capacity per pound than just the heat absorbed by the solid to liquid transition. The ice is produced in batches in horizontally oriented freezing trays, wherein the batches are then dumped automatically from the freezing trays.
Because the freezing trays are horizontally oriented, the water is dripped at a uniform rate, unlike cascading water flowing down vertically oriented freezing trays. These he horizontally oriented freezing trays can also be used as counters for displaying objects kept at cold temperatures, such as fish at a fish market or retail store. Moreover, these horizontally oriented freezing trays can be stacked horizontally one on top of each other for maximum use.
The rapid cycle time achieved insures very good capital efficiency as the weight of ice produced per day is high with respect to the cost of the apparatus.
Key elements of this invention that contribute to its superior performance include the design of the freezing trays which form an integral evaporator, as well as the method of dumping the ice product by rotating the tray from the horizontal to a vertical position. This rotation is facilitated by the use of flexible coolant hose connections to the freezing trays.
By cycle reversal (similar to a heat pump cycle), hot refrigerant is directed into the evaporation spaces in the trays for a brief xe2x80x9cthawxe2x80x9d cycle which creates a thin layer of water at the interface between the ice segment and the tray surface thereby dislodging the ice segment while the tray is in the vertical position with the water layer acting as a xe2x80x9clubricantxe2x80x9d to further aid in the dumping process. Since the xe2x80x9cthawxe2x80x9d cycle has very high heating power causing a high temperature difference between the heated tray surface and the ice segment, this cycle is short, and the heating of the ice surface is therefore localized to a thin liquid interface layer which quickly refreezes upon being dumped due to heat transfer to the interior of the supercooled ice segment.
Therefore, to summarize the key features, integral evaporation channels within the horizontally oriented freezing trays contribute to short freezing cycles; rotation of freezing trays is facilitated by coolant hose connections; dumping of ice product is accomplished by refrigeration cycle reversal heating freezing trays internally; product produced is convenient sized ice segments that are supercooled.